I. Field of the Invention
This invention relates to a novel, modular, bone grinding apparatus, a method of using the apparatus and a method of making the apparatus. The bone grinder and ground bone product produced by this apparatus is superior in a number of respects to currently available ground-bone products.
II. Background
Grinding capabilities used in tissue banking and transplant surgery during the last two decades has been marginal. The types of grinders available did not produce variable particle sizes and shapes in an efficient, speedy and reproducible manner. Even one of the most popular grinders used today in the operating room is driven by a hand crank, which leaves a lot to be desired in terms of ease of use, safety, productivity and reproducibility of product. However, these distinctions aside, the use of known bone grinders in the operating room leaves much to be desired. They are not modular and do not allow for minimal disassembly for sterilization purposes and ease of sterile reassembly.
Ground bone is a product that is finding ever increasing use in the orthopaedic and other arts. Typically, ground bone is used to augment or repair defects in a recipient's bone during various types of implantation or other orthopaedic procedures. Production of this product is currently dependent on a number of machines, none of which fully meet the needs of the practicing orthopaedic surgeon, and none of which display the several advantageous features which comprise the device of the present invention. In particular, in reviewing the needs of surgeons and the exigencies of working with a living tissue such as a patient's own bone that needs to be ground in the operating room milieu, the available grinders are found to be wholly inadequate.
Examples of known devices can be found in DE 3808409, wherein a bone mill was disclosed which has a barrel-shaped grinding head which produces bone shavings. Unfortunately, such a grinding head is inefficient, and is only capable of producing a small amount of ground bone at a time of approximately one uniform particle size. In FR 2712483, there is likewise described a bone grinder which has a rotating grating cylinder, also capable only of producing ground bone of one approximately uniform particle size. In FR 2199271, there is described a grinding mill with a toothed rotor wherein two co-axial grinding wheels having conical surfaces grind material fed into the grinder. In U.S. Pat. No. 4,252,282, there is disclosed a "double-roll crusher" for crushing bones. However, a complete bone grinding apparatus for production of ground bone suitable for orthopaedic applications is not disclosed. Finally, it is known that certain bone mill manufacturing companies have produced bone grinding devices which, from the available product literature, appear to be quite similar to the DE 3808409 and FR 2712483 devices. Included in this group are the bone grinders produced by DePuy Inc., and Tracer Designs, Inc.
In the hands of the instant inventors, it has been found that available models of bone grinders have a number of unacceptable limitations, particularly when very scarce resources are available, such as when autologous bone is to be ground in an operating room setting for use in a patient whose own bone is to be ground and reimplemented in the course of surgery. For example, one known model employs a piston-driven, saw blade shaped grinder/cutting head. Frequent jamming of this device and metal fragmentation has been experienced. Continued hammering of the air-driven piston of the device by the operator's fist is required to produce the blasts of air to drive the saw blade.
In another known grinding device, available at the rather high cost of approximately $9,000.00, the grinding occurs by crushing and cutting by a hand crank driven grinding head. Typically, only rather muscular operators may use this device with success and the potential for binding, along with the overall large size of the grinder itself, make the device less than optimal for operating room settings. In addition, the device is only capable of producing bone particles of one size.
None of the known devices provide for a bone grinder having a modular grinder head that can easily be removed from a grinder and which can be separately sterilized, brought into the operating room, and snapped into place in an available grinder.
Accordingly, the present invention provides a novel bone grinding device which displays a series of advantageous features not found in the above published documents or in the known commercially available bone-grinding devices. This novel device better meets the demanding requirements of the operating room procedures which currently utilize inadequate grinder devices. This device likewise meets the high-volume needs of tissue banks worldwide for reproducible and efficient production of ground bone products.